A convenient analysis for the thickness variation of coextruded film has been developed using an infrared absorption with compensator. The following equation was found to be applicable for the ethylene-vinyl acetate copolymer (EVA)/low density polyethylene (LDPE) two-layer film;
(D₁₇₄₀/D₁₄₆₅)(l-l_r)(/(d-d_r)=K
where D₁₇₄₀ and D₁₄₆₅ are the absorbances of the absorption bands at 1740cm^-1 and 1465cm^-1, l and l_r. are the thicknesses of the sample and compensator, d and d_r are the EVA layer thicknesses of the sample and compensator, respectively, and K is a constant.
The equation was found to be valid in both cases of the measurements with and without compensator by FTIR.
The thickness variation of EVA/LDPE coextruded films obtained by the above equation shows good agreement with results obtained by the DSC (differential scanning calorimetry) and density measurement method.

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Flexural test specimens were injection-molded from random or block polypropylene copolymers with various ethylene contents at cylinder temperatures of 200∼320°C. Properties such as flexural modulus (FM), flexural strength (FS), heat distortion temperature (HDT), Izod impact strength (IIS), and mold shrinkage (MS), and higher-order structures such as crystallinity (X_c), thickness of skin layer (ST), a*-axis-oriented component fraction ([A*]), and crystalline orientation functions were measured. The relationships between these properties and structural parameters were investigated.
These properties decreased with increasing cylinder temperature. FM, FS and HDT were decreased by copolymerization with ethylene, in particular, by random copolymerization. IIS was increased by copolymerization with ethylene. MS was decreased by random copolymerization and slightly increased by block copolymerization.
X_c was decreased and [A*] was increased by copolymerization, in particular, by random copolymerization. ST and crystalline c-axis orientation function f_c decreased with increasing cylinder temperature and ethylene content.
Rectilinear relationships between the properties and ST or f_c were obtained for each sample. This means that the properties cannot be unified only with degree of molecular orientation and the character of sample still remains. The character of sample is assumed to originate from higher-order structures beside molecular orientation, for example, crystallinity, spherulite size, and thickness of lamellae.

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Flexural test specimens were injection-molded from random or block polypropylene copolymers with various ethylene contents at cylinder temperatures of 200∼320°C. Distributions, in the flow direction, of higher-order structural parameters such as thickness of skin layer (ST) and crystalline orientation functions and distributions, in the thickness direction, of higher-order structural parameters such as crystallinity (X_c), β-crystal content (K), and crystalline orientation functions were investigated.
ST and crystalline c-axis orientation function f_c decreased with increasing distance from the gate and with increasing ethylene content. X_c was low at the surface region and increased toward the interior. X_c was decreased throughout whole range in the thickness direction by copolymerization, in particular, by random copolymerization. K value was decreased by block copolymerization and was nearly zero for random copolymers. f_c was high at the surface region and decreased toward the interior. The higher the cylinder temperature and ethylene content, the lower was f_c at the surface region. There were cases at high cylinder temperatures where a shoulder or a peak of f_c was observed at a middle point in the thickness direction, which is assumed to be caused by secondary flow during cooling and pressure holding process.

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